The present invention relates generally to lighting control systems. More specifically, the present invention relates to a computer-based system for controlling power to multiple ac lighting loads.
Lighting loads in a large office building are typically controlled from a central location by a computer programmed with proprietary software. The computer can be programmed to turn on all office lighting loads before the start of business and turn off all of the office lighting loads after business hours. In addition to scheduling the times at which the lighting loads are turned on and off, the computer can also be programmed to perform annunciation of load status, central monitoring and reporting to ensure that the building is operating as efficiently as planned.
The computer typically interfaces with a plurality of transformer relays, which are located in junction boxes throughout the building. The computer can control each relay to apply or remove power from its associated lighting load and thereby turn its associated lighting load on or off. A lighting load can include a single light or multiple lights. The relays and, therefore, the lighting loads can also be controlled by wall-mounted switches and sensors distributed throughout the building. Such a system including a plurality of intelligent relay-based lighting control system is available from the General Electric Company under the names "Total Lighting Control" system and "TLC" systems.
However, controlling the lighting loads from a central location can cause problems for those people who come to work early or work late into the night. When the computer turns off the lights, some of the people inside the building will be left in the dark. Naturally, they will want to turn the lights back on. However, turning the lights back on can pose more than a mild inconvenience. A person must set aside his work, walk over to the light switch and flip on the switch. In a large work area having many different lights, finding the correct switch can be a challenge. Some lighting control systems do not even allow the lights to be manually overridden.
Instead, a facilities management is called and asked to turn the lights on. Hopefully the response will be prompt.
There are phone-based lighting control systems that allow a person to turn on the lights by dialing up a certain number. These phone-based systems map each available lighting load onto a corresponding phone number. However, such artificial phone number mappings are non-intuitive. For instance, a person might be required to memorize or look up a twelve-digit phone number in order to use the phone-based lighting control system. For this reason alone, the phone-based systems tend to be cumbersome to use. Additionally, typical phone-based lighting control systems do not allow the intensities of the lighting loads to be varied.